At 10 am., an explosion occurred in a chlorine manufacturing unit undergoing repair works (on the electrical network of the installation). A safety fuse wire fused, thereby closing the shutoff valve (safety closed) which was mounted in the output of a gasometer jacket towards the collector over the piston-compressor.

The gasometer jacket continued to be filled with electrolytic hydrogen until the peak load was reached in the storage vessel, thereby closing the hydrogen control valve. An underpressure was thus created in the condenser aspiration pipe because the condenser had been stopped (safety shutoff).Back flowing air arrived to the high pressure condenser, mixed with hydrogen to form an explosive gas which autoignited.

The 2 plant keepers, which were in the near building, were seriously injured by an iron pieces breaking into the building made of bricks. The building, 2 pressure vessels, pipes and other parts of the plant were largely damaged, amounting to 3 M euros. The building of the compressor plant wil be rebuilt in light structure (design change).